1. Field of the Invention
The present invention relates to a foil material for the storage of hydrogen in materials capable of bearing hydrogen, i.e. a hydrogen storageable material.
The use of hydride formers for the storage of hydrogen is known. Utilized, in particular, are metal granulates. In the metals, the hydrogen is stored at the locations of the interstices in the crystal lattice to provide for the formation of metal hydride. Coming into consideration for technological applications are metals or metal alloys which possess a high storage capacity. The metal granulates are filled into a pressure tank, and then charged with hydrogen under a gas pressure which can range up to about 100 bar. Hereby, through the formation of systemic hydrogen superstructures in the crystal lattice, the density of the hydrogen can exceed that of liquid hydrogen. When the pressure is lowered, the storage material will then again discharge the hydrogen, which is stored in an atomic form in the metal, into the gas chamber of the pressure tank. With respect to the foregoing, reference may be had to H. Wenzl, "Metall-Wasserstoffkristalle in Festkorperforschung und Energietechnik", Annual Report of the Kernforschungsanlage Julich GmbH, 1976/1977.
2. Summary of the Prior Art
In order to render the metal granulate receptive to hydrogen, it is necessary to create metallic surfaces which do not evidence oxide layers or other impurities which would be disruptive to the hydrogen permeation. Such surfaces are produced through activation of the metal granulate. For this purpose, the metal granulates are heated in a hydrogen atmosphere and subsequently evacuated, whereby microfissures with surfaces free of oxides are formed in the material. Ascertained to be particularly suitable have been such FeTi alloys which tend towards embrittlement, as referred to in German Pat. No. 28 40 265.
Notwithstanding all efforts which have been expended to simplify the activation processes, as exemplified by reference to German Laid-open Patent Application No. 30 22 708, the activation process complicates the handling of the metal granulate storage container. Moreover, not all suitable hydride formers allow themselves to be activated in the desired manner. The material selection and the correlation of the storage material with the technological requirements are also quite restricted.
In addition thereto, the loading and unloading of the storage material involves significant changes in heat. Thus, the loading sequence takes place exothermally, whereas the unloading is carried out endothermally. The compressed-gas storage containers which are filled with metal granulate, as a result thereof, are equipped with heat exchangers which facilitate cooling or heating of the metal granulate in the compressed-gas storage container for the support of the currently desired hydrogen exchange in the metal. The speed of the loading and unloading procedure in the compressed-gas storage container is thus dependent upon the quality of the heat exchanger; in effect, upon the attained heat transfer and upon the heat conductance. The construction of the compressed-gas storage container and its function is, as a result, quite complex.